Patent Document 1 discloses a substrate processing apparatus that cleans the outer circumferential portion of the substrate using a brush. This substrate processing apparatus includes a spin chuck that rotates the substrate about a rotation axis passing through the central portion of the substrate while holding the substrate horizontally and a brush moving mechanism that presses a drum-shaped brush against the outer circumference of the substrate held by the spin chuck. The brush is pressed against the lower surface outer circumferential portion of the rotating substrate, and thereafter pressed against the upper surface outer circumferential portion of the rotating substrate.